In conventional direct-current circuit breakers that interrupt direct current, because, unlike alternating current, direct current does not have a current zero point, a current zero point is formed by superimposing resonance current from a commutation circuit composed of a capacitor and a reactor and the direct current is interrupted at the current zero point. Such methods of forming a current zero point include a forced commutation method (for example, Patent Literature 1) in which a commutation circuit composed of a capacitor and a reactor is connected in parallel with an interrupting unit and the resonance current with the reactor due to the discharge of the charge stored in the capacitor in advance is superimposed on the direct current, thereby forming a current zero point, and a self-commutation method (for example, Patent Literature 2) in which a commutation circuit composed of a capacitor and a reactor is connected in parallel with an interrupting unit and a current zero point is formed by using a self-oscillation phenomenon based on the interaction between an arc and the commutation circuit.